All of the values in the input array are used. The input array is first
histogrammed using numbins bins. The bin containing the median is
selected by searching for the halfway point in the cumulative histogram.
The median value is then computed by linearly interpolating across that
bin.

Parameters :

a : array_like

Input array.

numbins : int

The number of bins used to histogram the data. More bins give greater
accuracy to the approximation of the median.